In traditional practice of internal martial arts, like tai chi, movement often involve raising one's feet before stepping forward. The raised feet will cause the body to lose some chi - if not in very slow focused practice at least in actual normal speed movement.
In my own teaching, I always start with prior training of slow (or very slow) tai chi walk, to open my student's hip joint (Kua) before proceeding with friction walk. Indeed friction walk is more "advanced" in the sense that one can't reap its full benefit without a foundation in tai chi walk. The Kua must be loosened before it can generate powerful chi during friction walk.
What are the important points to note in friction walk, besides prior training in tai chi walk?
- There must indeed be friction! The feeling of friction (the concept of internal feeling is of paramount importance in the internal arts) is created through controlled weight to the feet/sole of the advancing leg.
- The body must be moving at a fixed horizontal level.
- The pair of stretched hands are for body balancing and internal chi balancing.
- Weight distribution on feet: about 90/10.